With bars in general many of the skills are timing related where additional strength can in a way be a hinderance
Personally I don't know if I'd agree it has to be a hindrance. I think with strength, it's easier to learn the correct technique if you're corrected. If you lack strength, you may start compensating and that can form bad habits.
In the example you gave, yes if you can muscle up a kip and you don't get corrected on it, that can cause trouble. But if you lack the ab strength to pull your legs to the bar, you may tuck your legs to do this and that can form a bad habit too if not corrected.
Personally, I think for bars you need strength, endurance and technique. Both the explosive strength and endurance are important. Without endurance you won't get through your routine, but without explosive strength you can't get the power in some elements that you need.
At every meet, she bends her arms when she reaches the low bar, causing her drag her feet in her kip out of the skill.
This could be all kinds of issues, it could be strength, endurance or technique. Some things she can maybe look at:
- Does she eat/drink enough in general and at meets? (Endurance and strength depend on good nutrition too)
- Does she bend her arms when she's practising the bail in isolation? If not, then it could be an endurance issue or an issue with how she gets out of the skill before the bail. For example if the skill before the bail ends nearly in dead hang, it'd be hard to get a good bail out of it.
- It could be an issue with the bail: if she ends it in the wrong position then bending her arms may be the only way to catch the bar.
- It could be arm strength or body awareness: does she bend her arms a lot on other skills, such as handsprings or on vault?
- If she has the issue even when she doesn't bend her arms, it could be ab strength.
Really, with so many possibilities it's something for her and her coach to sit down and have a good look at.
I'm not a coach though, so take what I'm saying with a grain of salt.